A $1.4 billion spacecraft is closing in on Saturn, preparing to surf its rings and moons--especially mysterious Titan

Saturn has been ready for its close-up for a long time. On June 30 the planet is going to get it as the $1.4 billion Cassini-Huygens spacecraft, after a journey of 2.2 billion miles, fires its retrorockets and puts itself into Saturnian orbit.

It's the start of a four-year tour, during which the ship will make at least 76 loops of the planet and engage a dozen cameras and instruments. NASA will be able to tweak the trajectory of the orbiter so it can slalom among nine of Saturn's 31 moons. The grandest of the satellites is Titan, which has long...